This invention relates to fractionation. In one of its aspects this invention relates to the fractionation of a mercaptan-containing stream containing both methanol and water. In another of its aspects this invention relates to fractionation apparatus. In still another of its aspects this invention relates to fractionation procedures to obtain overhead and bottoms streams from the fractionation containing a minimum of water.
The usual commercial processes for producing methyl mercaptan, whether using hydrogen sulfide and methanol as reactants as in U.S. Pat. Nos. 2,822,400 and 3,792,094 or in a combination process in which there is a reaction of carbon disulfide and hydrogen and a reaction of hydrogen sulfide and methanol, produce a reactor effluent containing both water and unreacted methanol along with the desired methyl mercaptan product and unreacted hydrogen sulfide. To remove the hydrogen sulfide, the reactor effluent is subjected to a fractionation. The presence of methanol changes the solubility of water in the organic phase in such a manner that the fractionation to strip hydrogen sulfide from the effluent cannot be operated so that dry overhead comprising hydrogen sulfide and a dry bottoms product comprising methyl mercaptan can be obtained. A method for manipulating the fractionation of an effluent stream containing hydrogen sulfide, methyl mercaptan, methanol, and water has now been developed.
It is therefore an object of this invention to provide a method for separating a feedstock comprising hydrogen sulfide, methyl mercaptan, methanol, and water to obtain a minimum of water in the overhead and bottoms streams from the fractionation process. It is also an object of this invention to provide an apparatus by which such a separation can be accomplished.
Other aspects, objects, and the various advantages of this invention will become apparent upon study of this specification, the drawing, and the appended claims.